Many mobile communication devices need to be able to operate using more than one system protocol. For example, a mobile device moving from one geographic area to another may need to switch from one communication system protocol to another communication system protocol in order to maintain communication. In such a scenario, a mobile unit may be actively communicating with a base station (active base station) utilizing a first communication system protocol (e.g., a 3GPP communication system protocol). When the mobile unit moves out of the coverage area of the active base station, it may need to switch to an idle base station using another communication system protocol (e.g., another 3GPP system, 3GPP2 or IEEE 802.11 communication system protocol). In such hybrid operation, where a mobile node contains transceivers for more than one spread spectrum technology, the mobile needs to acquire overhead information in order to become active on the idle base station.
An example of this is a hybrid Long Term Evolution/CDMA Evolution Data Only revision A (LTE/EV-DorA) phone, active on LTE, performing system selection and pilot maintenance on an (EV-DOrA) system. The hybrid mode phone can scan the idle system for pilots, but cannot stop operating on the active system long enough to acquire system overhead information from the common signaling channels of the idle technology. For example, the acquisition of all overhead information on EV-DOrA systems can take at least 1.28 seconds, which can kill all communication on the active system. Therefore a need exists for a method and apparatus for obtaining overhead information by a mobile unit without interrupting the active system's operation.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. Those skilled in the art will further recognize that references to specific implementation embodiments such as “circuitry” may equally be accomplished via replacement with software instruction executions either on general purpose computing apparatus (e.g., CPU) or specialized processing apparatus (e.g., DSP, dedicated logic gates). It will also be understood that the terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.